The invention relates to a magnetic disk apparatus using a magneto-resistive element as a read head and to a reproducing method of the magnetic disk apparatus. More particularly, the invention relates to a magnetic disk apparatus using a combination head integratedly comprising a read head using a magneto-resistive element and a write head using an inductive head and to a reproducing method of the magnetic disk apparatus.
In recent years, in association with a large capacity of a magnetic disk apparatus as an external memory apparatus of a computer, a magnetic head of a high performance is required. As an apparatus which satisfies such a requirement, attention is paid to a magnetic disk apparatus having what is called an MR (magneto-resistive) head using a magneto-resistive element which does not depend on a peripheral velocity of a recording medium and which can obtain a high reproduction output.
Hitherto, in a magnetic disk apparatus having a swing type positioning mechanism to which an MR head is attached, as shown in FIG. 1, by rotating a rotary positioner 22 by a voice coil motor, an arm 74 is swung and a magnetic head 14 is positioned. FIG. 2 is a diagram enlargedly showing a conventional magnetic head. The magnetic head 14 is provided at an edge surface of a slider 88 which is supported at a tip of the arm. As shown in FIG. 3, the magnetic head 14 is constructed by an inductive head and an MR head. The inductive head is constructed by an upper magnetic pole 76, a coil 78, and a lower magnetic pole 80 and performs a magnetic recording of a recording track 75 having a width of the lower edge surface of the upper magnetic pole 76. An MR element 25 serving as an MR head is arranged behind the inductive head. A pair of leads 84 (not shown) and 85 are pulled out from the MR element 25. A reproduction output is derived on the basis of a resistance change of the MR element 25 due to a recording magnetism of the recording track 75. As a reproduction output by the MR element 25, a high reproduction output is obtained at any cylinder positions without depending on a change in peripheral velocity at the cylinder position depending on a radius of the recording medium.
In a combination type magnetic head in which the recording magnetic poles 76 and 80 and the MR element 25 are separately constructed and are away from each other by a few pm, a relative position between an inner recording track 112 and an outer recording track 114 by the recording magnetic pole 76 changes due to the positioning by the rotary positioner 22 in FIG. 1 as shown in FIG. 4A. Therefore, in order to on-track the MR element 25 to both of the inner recording track 112 and outer recording track 114, a center 118 in the track width direction of the recording magnetic pole 76 and a center 120 in the track width direction of the MR element 25 are purposely deviated by only a micro distance .alpha., thereby constructing a magnetic head so that the MR element 25 is on-tracked onto a recording track in a whole region from the inner position to the outer position.
However, in such a conventional magnetic disk apparatus in which the combination head integratedly comprising the MR head and the inductive head is positioned by the rotary positioner, the head is arranged for each of both recording surfaces of the recording medium. For example, when the heads are vertically arranged, it is necessary to deviate the recording magnetic pole 76 and MR element 25 in the reverse direction for the head on the up-side and the head on the down-side. Namely, FIGS. 4A and 4B show an up-head 14-1 and FIGS. 5A and 5B show a down-head 14-2. As shown in FIGS. 4A and 5A, when both heads 14-1 and 14-2 are seen as plan views, the center 120 of the MR element 25 is deviated from the center 118 of the recording magnetic pole 76 toward the outer side by the predetermined amount .alpha.. However, since the down-head 14-2 corresponds to the head which is obtained by turning over the up-head 14-1 in FIG. 4B and oppositely arranging as shown in FIG. 5B, it is necessary to oppositely deviate the recording magnetic pole 76 and MR element 25. Therefore, it is necessary to prepare different masks in the head manufacturing step and, further, it is necessary to individually assemble the up-head and down-head to the arm in the head assembling step. There are problems such that the manufacturing step is complicated and the costs rise.